The orderly and efficient movement of objects increases safety by preventing collisions and maximizes time and energy savings. Using vehicle traffic as an example, the majority of vehicle accidents occur at or in the vicinity of an intersection where roadways converge or cross. In addition, time and energy (e.g. momentum, fuel, battery power, etc.) is wasted by vehicles idling at an intersection needlessly waiting for a traffic signal to provide a legal right-of-way for the vehicle to proceed. Furthermore, traffic congestion is increased by traffic signals that are not responsive to real-time vehicle traffic and weather conditions, leading to frustration and potential “road-rage” among vehicle operators.
Numerous different systems and methods have been developed and deployed for monitoring and/or controlling vehicle traffic at an intersection. Timers have long been used to facilitate the flow of traffic through an intersection by controlling the operation of a traffic signal. For example, a timer can be programmed to change a traffic signal at predetermined intervals of time based on a study of the vehicle traffic at an intersection over an extended period. However, timers passively control the traffic signal according to historical traffic patterns instead of real-time vehicle traffic. Furthermore, timers do not account for atypical weather conditions, or for accidents and other randomly occurring events along the roadways converging at the intersection, such as slow-moving vehicles and pedestrian traffic. In addition, timers are subject to malfunction, which can lead to a disruption of the flow of traffic and potentially an interruption in the synchronization with other traffic signals along the roadways until proper operation of the timer is restored.
It is also known to utilize electrical or mechanical triggers to monitor vehicle traffic and control the operation of a traffic signal, especially in a rural area and at an intersection for a cross street having significantly less vehicle traffic than the through street. Most such intersections utilize loops or coils of wire buried within or beneath the roadway to trigger a traffic control signal. When a metal object, such as a vehicle, passes over the loops or coils of wire, an electrical charge is created that triggers the traffic control signal to change after a predetermined time. Mechanical triggers include weight (pressure) sensors or magnets positioned within or beneath the roadway approaching the intersection. The weight sensor or magnet detects the presence of a vehicle stopped on the cross street waiting to enter the intersection and changes the traffic signal after a predetermined time to allow the stopped vehicle to proceed safely through the intersection. As a result, existing triggers are merely reactive to the physical presence of a vehicle at an intersection and do not anticipate the volume of arriving vehicles and change the traffic signal in advance. Oftentimes, the trigger is configured with a delay to account for a vehicle that stops momentarily at the intersection before performing a right turn on a red light traffic signal in instances that a “right turn on red” is permitted. Similarly to a timer, a traffic signal trigger may be configured to be overridden and operated by a transient signal, for example an electrical, optical, radio frequency (RF), ultrasound or the like signal, transmitted by an emergency vehicle to allow the emergency vehicle to proceed through the intersection without stopping for a red light traffic signal.
It is also known to utilize optical images obtained from one or more photo and/or video cameras positioned in the vicinity of an intersection to monitor and control a traffic signal at the intersection. However, photo and video cameras record bitmap, or raster, images defined by a series of pixels that require large amounts of computation power, time and data storage, even for two-dimensional (2D) landscape images that lack sufficient accuracy and resolution for efficient traffic surveillance and control. As a result, the algorithms currently available for processing optical images recorded by photo and video cameras are not fast enough to control a traffic signal in response to real-time vehicle and pedestrian traffic, let alone real-time ambient weather conditions. Furthermore, because existing cameras lack the ability to discern depth, they fail to provide a true three-dimensional (3D) rendering of the area surrounding the intersection. In addition, conventional photo and video camera surveillance systems lack the capability to analyze vehicle traffic and accurately predict vehicle movements and traffic patterns without human intervention. As a result, such systems and methods are uneconomical and impractical for monitoring and controlling the flow of vehicle traffic at less traveled intersections, for example rural intersections.
In view of the desirability for orderly and efficient movement of objects, and in particular vehicles and pedestrians through an intersection, a system and method is needed for monitoring vehicle traffic and controlling traffic signals that increases safety and maximizes time and energy savings. More specifically, a system and method is needed that monitors vehicle traffic and controls a traffic signal in response to real-time vehicle traffic and real-time ambient weather conditions. There exists a further need for such a system and method that does not require a large amount of computation power, time and data storage, yet operates in a fast, accurate and reliable manner. There exists a particular need for a system and method for monitoring vehicle traffic and controlling traffic signals that operates autonomously, and therefore, is economical and practical for use at less traveled intersections.